Momentary slowdown device for high-speed blank holder presses



Jan. 25, 1949. R. J. LINDSEY MOMENTARY SLOW DOWN DEVICE FOR HIGH SPEEDBLANKHOLDER PRESSES Filed Dec. 6, 1944 2 Sheets-Sheet l INVENTOR-ROBERTQLLINMEY,

' AOEYJ Filed Dec. 6, 1944 1949- J. LlNDSEY 2,459,88

MOMENTARY S W DOWN DEVICE FOR HIGH SPEED BLANKHOLDER PRESSES 2Sheets-Sheet 2 INVZENT noazmazmmzv,

. MT RNEW Patented Jan. 25, 1949 MOMENTARY SLOWDOWN DEVICE FORHIGH-SPEED BLANK HOLDER PRESSETS Robert J. Lindsey, Mount Gilead, Ohio,assignor to H-P-M Development Corporation, Wilmington, Del a corporationof Delaware Application December 6, 1944, Serial No. 566,926

4 Claims. (Cl. 113-45) This invention relates to control systems forblankholder presses. More particularly, this invention relates to acontrol system adapted to provide an improved operation of a blankholderpress during the retraction stroke thereof.

In blankholder presses wherein the blankholder platen is carried by themain platen, the latter picks up the former during the retraction'strokeof the press and returns it to its idling position. Usually, especiallyin the case of deep draws, the main platen has attained its fullretraction speed before it reaches the position where it picks up theblankholder platen. The blankholder platen having considerable weight,the result of the main platen engaging it at full retraction speed is tocreate noise and vibration and, possibly, breakage of parts.

Accordingly, it is a primary object of this invention to provide acontrol system for a blankholder press which substantially prevents themain platen of a blankholder press from picking up the blankholderduring the retraction stroke with a shock.

It is another object to accomplish the foregoing object by a fluidoperable means.

It is another object to provide a control system for a blankholder presswhich has an automatic slow-down of the main platen during the advancingstroke and also during the retraction stroke thereof.

It is another object to provide cushioning means between the main platenof a'blankholder press and the blankholder thereof operable to effectshockless engagement of the said blankholder by the main platen duringthe retraction stroke.

These and other objects and advantages will become more apparent uponreferences to the accompanying drawings, in which:

Figure 1 is a view of a blankholder press and control system therefor,shown diagrammatically;

Figure 2 is an enlarged sectional view showing a portion of the mainplaten of the press of Figure 1 and the cushioning means associated withthe blankholder pick-up rod;

Figure 3 is a section taken on the line of 3-3 of Figure 2; and

Figure 4 is a diagram of the electrical portion of the control system.

General arrangement A press adaptedto be controlled by the controlsystem of this invention comprises a main platen reciprocable toward andaway from a stationary bed, the platen and bed mounting cooperating dieportions so that a workpiece may be shaped or drawn by the cooperationof the said die portions.

The platen has associated therewith a blank-. holder platen which issupported by the main platen by a plurality of rods and is permitted tomove toward the main platen by a plurality of piston-cylinder meanswhich serve to create the proper blankholding force, this latterfunction being accomplished by the provision of a relief valve or valveswhich maintains a predetermined and proper pressure within the saidcylinders.

The aforementioned blankholder pick-up rods pass through lugs on themain platen which have cushion means therein so that the engagement ofthe main platen with the blankholder pick-up rods is substantiallyshockless.

According to this invention the main platen may be reciprocated by adouble acting fluid operable ram to which is attached a suitable sourceof fluid pressure such as a reversible variable fluid delivery pump.

The aforementioned pump is controlled by linkage operable to place thesaid pump in full or partial delivery position in either direction or inneutral. The linkage is actuated by a pistoncylinder arrangement whichis operated by pilot fluid conducted thereto from a plurality of pilotvalves.

The said pilot valves are most conveniently operated by electricalmeans, the electrical means comprising limit switches responsive topredetermined movements of the main platen or to predetermined relativemovements between the main platen and the blankholder platen.

According to this invention, one of the said pilot valves is actuated bya limit switch which is actuated just prior to the engagement of themain platen with the blankholder platen during the retraction stroke.The said valve is effective to actuate the piston-cylinder arrangementassociated with the pump control linkage to shift the pump to reduceddelivery position. Thus; the main platen is momentarily slowed downduring the retraction stroke to afiect the shockless cushionedengagement thereof with the blankholder platen.

Optionally, although not preferably, the slowdown of the main platenduring its retraction stroke may be accomplished by timing the intervalbetween the reversal thereof and the said slowing down.

Structural arrangement Referring to the drawings more in detail, Figure1 illustrates diagrammatically a blankholder press having a controlsystem according to this invention. The press comprises a bed I having adie cavity I2 therein, a-main platen I4 which carries the punch I6 and ablankholder platen I8 which is supported by the main platen by the rodsand 22.

The main platen I4 is attached to a ram 24 which terminates at its upperend in the piston 26 which is reciprocable in the cylinder 28.

The cylinder 26 is connected, at its upper end,

to the pump 30 by the conduit 32 and, at its lower end, to the pump 80by the conduit 34. The conduit 34 has a branch conduit 36 connectedtherewith which extends into the reservoir 38 and connects with theoutwardly opening check valve 40. Also connected with the lower end ofthe cylinder 28 is the pilot conduit 42 which connects with the surgevalve 44 and opens the latter in response to a predetermined pressure inthe lower portion of the cylinder 28.

Connected with the conduit 32 by a branch conduit 46 is a pressureswitch 48 which, in response to a predetermined pressure on the uppersurface of the piston 26, is adapted to open the circuit betweeen thewires 50 and 52.

The platen I4 comprises a plurality of cylinders 54 within which arereciprocable the plungers 56, the latter being connected with theblankholder platen I8. The cylinders 54 are connected by a conduit 58with an adjustable relief valve 69 and an inwardly opening check valve62, the other sides of which are connected with the resevoir 38. Duringrelative movement of the platens toward each other, the fluid in thecylinders 54 is expelledthrough the relief valve 69 and, during relativemovement of the platens away from each other, the cylinders 64 arefilled through the check valve 62.

The pump 30 comprises the servomotor 64, the actuation of which iseffected by the control piston rod 66. A lever 88 is pivotally connectedwith the rod 66 and is rotatably supported on the servomotor 64 by thefloating pivot I0. A drag link or pitman I2 is pivoted to the levers 68at I4 and, to the lever I6 at I8. The lever I6 is secured to astationary pivot at 80 and is also pivotally connected at 82 to the rod84 which is integral with the plunger 86 reciprocably mounted in thebore 88 of the cylinder generally indicated at 90.

The opposite end of the lever 16 terminates in the angular portion 82which is adapted to be engaged by the arm 94 of the platen I4 when thelatter is in its fully retracted position.

The cylinder 80 comprises, in addition to the bore 88, the bores 96, 98,I00 and I02, these being separated by apertured partitions within thecylinder 90.

Reciprocably mounted in these separating partitions are the plungersI04, I06 and I08, each of which has a somewhat greater effective areathan the plunger 86.

A conduit II fl'connects into the cylinder 90 at the extreme right handend thereof and also connects with the discharge port of the pump II2whose suction port is connected with a reservoir "4. The discharge portH2 is also connected with the inlets of a plurality of valves H6, H8,I20 and I22 by the conduits I24, I26, I28 and I30. respectively. Each ofthe aforementioned valves comprises a valve member I32, I34, I36 and I38which is urged downwardlyby. asuitable yielding means such as a spring.

Each valve piston is connected with't'hearr'nature of a solenoid which,when energized serves to u'rgethe valve member upwardly against j thevalve member I32 into position to interconnect the conduits I24 and I50thereby actuating the piston I04. The valve H8 is similarly arrangedwith a discharge port I52 and a service line I54 which leads into thechamber I00 of the valve 90. The valve I36 has an exhaust port I56 and aservice line I58 which connects with the chamber 98 of the valve 90. Asin the case of the valve I I6, the energization of the solenoids I42 andI44 is adapted, respectively, to shift the'valve members I34 and I36into position to connect the conduits I26'and I54 and the conduits I28and I58. The plungers I06 and I 08 are thus, respectively, actuated.

The valve I22 comprises an exhaust port I68 and a service line I62 whichleads into the chamber 96 of the valve 90. The spring in the valve I22normally urges the valve member I38 into position to connect theconduits I30 and I62 so that the piston 86 is normally urgedrightwardly. Energization of the solenoid I46 is adapted to move thevalve member I38 into position to connect the conduit I62 with theexhaust port I60 thus exhausting the chamber 96.

The exhaust ports I48, I52, I56 and I60, if the fluid pumped by pump H 2is air, may exhaust into the atmosphere and, if the fluid is a hydraulic medium, may be connected with the reservoir II4.-

Referring to Figures 2 and 3, there is shown the lugs or ears on theplaten I4 through which the blankholder pick-up rods 20 and 22 pass.These lugs comprise a recess I within which are mounted a plurality ofannular channel members I82 and a plurality of resilient annular membersI84, the latter comprising a rubberlike material.

A ring I86 rests on the top of the uppermost of the members I04 and isadapted to abut the collar I88 of the rod 22. A plate I closes the topof the chamber I 80 so that the ring I86 and resilient members areretained in place.

Mounted on the platen I4 adjacent the rod 22 is a limit switch 200 whichcomprises a roller 202 situated in the path of the collar I88. Theswitch 200 is so located that the roller 202 drops off the collar I88slightly before the latter engages the ring I86. The switch 200 isadapted, when actuated by the collar I88, to close a circuit from theline 204 tothe line 206 and also to the line 208.

This action occurs when the roller 202 is moved toward its dotted lineposition in Figure 2 and the switch is idle when the roller is movedupwardly from its Figure 2 position, this occurring when the collar I88is moved upwardly relative to the platen I4.

A second limitswitch .2I0 is located so as to be actuated by the platenat a predetermined position during its downward travel. The actuation ofthe switch 2 I0 is effective to close a circuit between the lines 2I2and 2I'4. The closing of this circuit is momentary and is reopened whenthe platen passes the said switch.

Referring to Figure 4, the electrical circuit by means of which thesolenoids of the various pilot valves are energized is shown. In thisfigure the supply lines are indicated at 220'and 222; Conneeted betweenthe said supply lines is the contactor solenoid 224 which is adapted tobe energized by the closing of the push button 226. The solenoid 224 ismaintained energized by a holding circuit which includes the blades224'. The solenoid 224 also closes the blades 224" which are seriallyconnected between the lines .220 and 222 with the solenoid I46.

Connected to the line 220 by the wire 2| 2 is the limit switch 2I0 whichis joined by the line 2I4 with the solenoid I40, the other end of whichis connected to the power line 222.

The limit switch 200 is connected between-the lines 220 and 222 inseries with the solenoids I46 and I44 and is adapted, upon beingactuated, to energize the said solenoids. c

A contactor solenoid 226 is connected in series with the push button 228with the power line and is adapted, when energized, to close the blades226' and 226", the former providing a holding circuit for the solenoid2.26 and the latter being serially connected with the valve solenoidI42. A push button 229 is provided in the holding circuit of thesolenoid 226 and is adapted to deenergize the said solenoid whenactuated.

Operation In operation, a working stroke of the press is instituted byclosing the switch 226. This energizes the contactor solenoid 224 whichholds on itself through the blades 224' and energizes the valve solenoidI46 through the blades 224".

Energization of the valve solenoid I'46 moves the piston member I38upwardly thus interconnecting the conduit I62 and the exhaust port I60.

The chamber 96 being exhausted, the pressure standing in the chamber 88is effective to move the piston 86 and piston rod 84 leftwardly thusactuating the linkage comprising the levers I6 and 68 to move piston rod66 of the servomotor 64 into position to bring about the full deliveryof the pump into the upper end of the cylinder 28. The platens I4 and I8are thus rapidly advanced toward work engaging position. Immediatelyprior to the engagement of the work by the blankholder platen I8 theswitch 2I0 is actuated to energize the valve solenoid I40. Energizationof the valve solenoid I moves the valve member I'32 into position tointerconnect the conduits I24 and I thereby supplying actuating fluid tothe chamber I02. The piston I 04 is thus actuated and, by means of itsabutting relationship with the piston I06 and I08 moves the piston 86rightwardly so that the aforementioned pump control linkage shifts thepump 30 into reduced delivery position. The downward movement of theplatens I4 and I8 is thereby checked, so that the engagement thereofwith the workpiece is accomplished at moderate speed and, therefore,without shock.

The switch 2) is deenergized as soon as the engagement with the work.has been accomplished, or slightly prior thereto, and the circuitreturns to its rapid advance position.

As the platen I4 continues downwardly with the blankholder platen I8 inengagement with the workpiece, the plungers 56 move into the cylinders54 and expel fluid therefrom through the relief valve 69 therebycreating the proper blank holding pressure. At the same time the rods 20and 22 move upwardly relative to the platen since they are rigidlyattached to the blankholder.

After the main platen has completed its work and built up apredetermined pressure in the upper end of the cylinder 28, the switch48 is opened, thereby deenergizing the contactor solenoid 224 and thevalve solenoid I46. The deenergization of the valve solenoid I46 againconnects the conduits I30 and I62 and thus brings about the supply ofpressure fluid to the chamber 96. The pressure in the chamber 96 urges.the piston 86 rightwardly and, through the pump control linkage,movesthe latter into position to deliver through the conduit 34 to thelower endof the piston 28. The ram 24 and main platen I4 thus commencestheir retraction stroke.

As the platen I4 moves upwardly, the collar I88on the rod 22 movesdownwardly relative to the said platen until it actuates the switch 200.Actuation of the switch 200 is effective simultaneously to energize thevalve solenoids I46 and I44. Energization of these solenoids bringsabout the supply of pressure fluid to the chamber 98 while exhaustingthe chamber 96. The exhausting of the chamber 96 permits the piston 86to move toward its forward delivery position while the supply ofpressure fluid to the chamber 98 moves the piston I08 into position toabut the stop piston 86 at a point such that the pump 30 is deliveringto the lower end of the cylinder 26 at a reduced rate.

Thus, the platen I4 moves into engagement with the collar I88 atreducedspeed. Simultaneously with or slightly prior to the engagement ofthe collar I88 with the ring I86, the switch 200 opens so as to permitthe pump control circuit to return the said pump into position todeliver at full rate into the conduit 34. During the interval that thepump is shifting from reduced delivery position into full deliveryposition, the platen I4,-through the cushion member I84 and the collarI88, is gradually accelerating the blankholder platen I8. Theblankholder platen I8 is thus picked up quietly and smoothly and withoutshock,

Should it be desired to halt the travel of the platen at any time duringits downward movement the switch 228 may be closed thereby energizingthe contactor solenoid 226 which holds on itself and energizes the valvesolenoid I42 through the blades 226".

The energization of the valve' solenoid I42 brings about the supply ofpressure fluid to the chamber I00 and actuates the piston I06 to movethe piston 86 into its neutral position thereby centering the pump 30and preventing the discharge therefrom in either direction. The downwardstroke of the platen may be resumed by opening the switch 229 whichdeenergizes the solenoids 226 and I42.

At the end of the retraction stroke the platen arm 94 engages theportion 92 of the lever I6 and moves the pump control linkage into aneutral position.

It will be apparent that various modifications can be made in thestructure shown without in 1. The combination in a blankholder press ofa main platen, a blankholder platen, a plurality of piston-cylindermeans operatively associatin said blankholder platen with said mainplaten, rods carried by said blankholder platen extending through saidmain platen and having collars thereon to limit the maximum spacing of.said platens while permitting movement thereof toward each other, motormeans for advancing said main platen into working position during whichtime said blankholder is moved toward said main platen and forretracting said main platen from said working position during which timesaid.

blankholder moves away from said main platen, means carried by said mainplaten to be engaged by one of said collars for retarding the speed ofmovement of said main platen immediately prior to the engagement thereofwith said blankholder platen through said rods and collars, and meanscomprising annular resilient elements encircling said rods andinterposed between said collars and said main platen whereby during theretracting movement of said main platen said blankholder platen ispicked up smoothly and without shock.

2. In a press, a main platen, a blankholder platen, piston-cylindermeans associating said platens, a rod attached to one of said platensand extending through the other for interconnecting said platens, acollar secured to said rod on the portion extending beyond said otherplaten for limiting the maximum spacing of said platens but permittingthe movement thereof toward each other, a recess insaid other platenaround said rod opening toward said collar, annular resilient means insaid recess to be engaged by said collar, fluid operable advancing andretracting means associated with said main platen for advancing and forretracting the same, a fluid source adapted selectively to deliver toone or the other of' other means operable in response to a predeterminedretracting movement of said main platen away from said blankholderplaten for actuating said control means to reduce the delivery thereofto said retracting means, the said other means including a limit switchcarried by said other platen and having its actuating element disposedto be actuated by said collar immediately prior to the engagement ofsaid resilient means by said collar. g

3. In a. press which has a main platen and a blankholder platensuspended therefrom by members which limit the maximum spacing of saidplatens but permit the same to move toward each other and in which themain platen has motor means for advancing it into working position andfor rapidly retracting it'from working position, the improvementcomprising providing means for momentarily retarding the retractingspeed of said main platen immediately prior to the engagement thereofwith said blankholder platen through said members andthereafterrestoring said main platen to its full retracting speed, said meanscomprising a limit switch and cam, one of which is carried by one ofsaid platens and the other of which is carried byone of said members.

4. In a press which has a main platen and a blankholder platensuspended, therefrom by members which limit the maximum spacing of saidplatens but permit the same to move toward each other and in which themain platen has motor means for advancing it into working position andfor rapidly retracting it from working position, the improvementcomprising providing resilient cushioning means between said members andone of said platens and also providing cooperating means on one of saidplatens and one of said members operable automatically and momentarilyto retard the retracting speed of said main platen in response to apredetermined spacing of said platens less than said maximum spacingthereof for effecting the engagement of said platens through saidmembers and said cushioning means at reduced speed.

ROBERT J. LINDSEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,439,209 Watson Dec. 19, 19221,891,121 Thoreson Dec. 13, 1932 1,902,063 Ferris Mar. 21, 19332,205,791 Dinzl June 25, 1940 2,117,264 Workman May 10, 1938 2,192,778Stacy Mar. 5, 1940 2,193,248 Ernst Mar. 12, 1940 2,234,009 Robinson Mar.4,1941 2,252,789 Van Dorn Aug. 1941 2,252,881 Ernst Aug. 19, 19412,294,451 Ernst Sept. 1, 1942 2,298,359 Ernst Oct. 13, 1942 2,325,146Muller 1 i July 27, 1943 2,350,884 Ernst June 6, 1944 2,361,496 PointerOct. 31, 1944 2,382,046

Flowers Aug. 14, 1945

